Recoil mechanism



De- 5 1944. c. E. SIMPSON RECOIL MECHANISM Filed April 20, 1942 2 Sheets-Sheet 1 APS Clprennee E. [Simps-un @3M d W f1/ M Dec. 5, 1944. c. E. SIMPSON RECOIL MEGHANISM Filed April 20, 1942 2 Shees-LdeerI 2 m. NN. .wml m d 2 on mm Nm mw M UFTI@ hn N., I mm om mm E Nm lurence E- Eil-upenn i! -zL/q f,/. M

Patented Dec. 5, 1944 BECOIL MECHANISM Clarence E. Simpson, Sprlngield, Mass.

Application April 20, 1942, Serial No. 439,658

(Granted under the act oi March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 8 Claims.

The invention described herein may be manufactured and used by or for the Goverment for governmental purposes, Without the payment to me of any royalty thereon.

This invention relates to a shock absorbing mechanism particularly adapted for use as a recoil mechanism for a firearm.

It is an object of this invention to provide an improved recoil mechanism for a firearm particularly adapted for mounting beneath the barrel of the firearm. Another object of this invention is to provide an improved recoil mechanism of a firearm which includes a breechA operating rod within its assemblage. Another object of this invention is to lprovide an improved recoil mechanism which will effectively and efficiently absorb the recoil forces of a firearm so as to permit shoulder firing of firearms of .60 caliber or larger.

Another object of this invention is to produce a hydraulic energy absorption means effective for energy absorption in two directions wherein the amount and rate of energy absorption for either direction may be independently and conveniently changed.

Another object of this invention is to provide an improved recoil mechanism for a firearm which utilizes a combination of spring and hydraulic energy absorption means.

A further object of this invention is to provide an improved recoil mechanism which also operates a breech closing mechanism; the recoil mechanism being eiective to absorb both recoil and counter-recoil shocks by a combination of spring and hydraulic absorption means.

A particular object of this invention is to provide an improved recoil mechanism for a firearm which may be quickly and easily disassembled from such firearm as a unit. It is a further object of this invention to provide a recoil mechanism which may be readily disassembled into its component parts with the use of a minimum number of conventional tools.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a longitudinal sectional view of the improved recoil mechanism assembled on the barrel vof a firearm.

Fig. 2 is the section taken along the plane 2-2 of Fig. 1.

Fig. 3 is the section taken along the plane 3--3 of Eig. 1.

Fig. 4 is the section taken along the plane 4-4 of Fig. 1.

Fig. 5 is a sectional view of the piston member utilized in the hydraulic cylinder shown in Fig. 1.

Fig. 6 is an outline view of a split washer utilized in the assembly of the hydraulic cylinder within the recoil mechanism.

Fig. 7 is a side elevational view showing the latching relation between the barrel and the breech extension member prior to firing of a cartridge While Fig. 8 is a similar view showing the lat-ching relation just prior to completion oi the counter-recoil movement of the barrel, and

Fig. 9 is an enlarged sectional view of an embodiment of the piston and cylinder providing unequal enengy absorption on the recoil and counter-recoil movements.

Referring to Fig. l, the improved recoil mechanism A is shown in assembled relation on the barrel B of a firearm. While this recoil mechanism is preferably utilized on a .60 caliber rie, it will be understood that this is merely a preferred application and its application to other calibers of firearms may be readily accomplished by mere change of the size or strength of its components.

The recoil mechanism is roughly cylindrical in shape and is particularly adapted for mounting beneath the barrel B although it should be understood that other mounting positions with respect to the barrel are possible and that only a preferred embodiment is shown. A long hollow cylindrical recoil tube I extends throughout the length of the recoil mechanism and is rigidly secured at its rear end to the barrel B by means of a fitting 2. The fitting 2 (Fig. 2) comprises a unitary structure having a large cylindrical opening 3 through which the barrel may be inserted and a transversely extending bifurcated portion 4 defining a smaller semicylindrical opening 4a between forklike extensions 4b and 4c. The large opening 3 is provided with interior threads 3a and a shoulder 3b which cooperate with threads 3c and shoulder 3d on the barrel B to detachably secure the fitting 2 to the barrel.

A bushing l is provided having one end detachably secured within the end of recoil tube I as by means of the threads la which engage interior threads Ia within the tube I. At the central part of the bushing 1, at the end of the thread 1a, there is provided a flange 1e which is of larger diameter than the opening 4a and tube l. By screwing the bushing 1 into the end of tube I, the collar 1e is thereby brought into engagement with the end of tube I. The other cup shaped member II.

end of bushing 1 is of suitable diameter to enter the opening 4a by passage between the extensions 4b and 4c of the bifurcated portion 4. The bushing lis snugly supported in the opening la by means of a. cylindrical nut member Ic which is screwed on to the threads Id on the end of the bushing. The head of this nut member Ic enters a countersunk portion 4d surrounding the opening 4a of tting 2. In this rposition, the ,flange 'le abuts against the front end of the portion 4 of fitting 2. Thus, the bushing 1, and hence the tube I, isrigidly supported within the opening 4a by tightening of the cylindrical nut 1c. It is apparent that by backing off the cylindrical nut 1c, the bushing "I, and hence the end of recoil tube I, may be dropped out of the fitting 2, or conversely, the barrel may be raised with respect to the recoil mechanism and freed from engagement therewith.y

On the forward end of the tube I, a collar 6 is snugly mounted. The collar B has a large diameter portion 6a and a front smaller diameter portion 6b. A bolt member 5 is threaded into the tube I and by means of its projecting head 5a prevents the collar 6 from slipping oif the end of I for a substantial portion of its length and is supported at its rear end by an inserted threaded cylindrical projection I0 of a hollow frame member 9. This frame member 9 is connected with the stationary portions of the firearm vin a manner not shown. In a shoulder weapon, for example, the frame member 9 will be rigidly connected to that portion of the firearm which engages the shoulder ofthe operator. Since the barrel generally has no other rigid connection with the stationary portions of the gun, the recoil or breech closing shocksA produced by the discharge and loading of a cartridge respectively must be substantially absorbed before transmittal to the frame member 9.

'The front end of the bearing cylinder 8, and hence the tube I, is supported by threaded en' gagement with the walls IIa of a surrounding transverse extending hollow cylindrical portion I2 which is slipped over the barrel B supporting the front end of the recoil mechanism thereby.

The interior surface of the opening I2 is provided with an unusual configuration which may be best described by separately considering the top and bottom semi-cylindrical portions formed by division of the opening I2 by an imaginary horizontal plane. The bottom portion then has a rear half surface I2a of cylindrical shape with such diameter as to closely engage the barrel B. The front half surface I2b is of a semi-conical shape, increasing in diameter towards its front. The top semi-cylindrical portion of opening I2 is likewise provided with a cylindrical surface I 2c engaging the barrel B, and a semi-conical surface |2d. However, the location of these top surfaces is exactly reversed with respect to the bottom surfaces; i. e., the cylindrical surface I2c is at the front and the semi-conical surface I2d is at the rear, with the diameter of the cone lncreasing toward the rear. With this construction, the barrel B will freely slide in a horizontal plane within opening I2, engaging cylindrical surfaces I2a and I2c. At the same time, it is possible to pivot the barrel clockwise (as viewed This member II has a in Fig. 1) within the opening I2. the extent ofl the pivoting being limited by the semi-conical surfaces. Such pivotal movement of the barrel, of course, cannot be accomplished until nut member 1c is backed oil, permitting the fitting 2 to be disengaged from the bushing 1 by the pivotal movement. After pivoting the barrel B. it can be withdrawn through the opening I2 and thus be entirely separated from the recoil mechanism A.

A hole IIc is provided in the base IIb of the cup-shaped member II. Into this hole the front portion Eb of collar B is permitted to enter. It should be emphasized that the base IIb does not act as a stop for longitudinal movement of the tube I to vthe front. When the barrel is in its most forward position permitted by the breech mechanism (not shown), there is slight clearance between base IIb and collar 6a.

' A recoil spring I4 is mounted within and supported by lthe bearing cylinder- 8, and operates between the end of projection I0 of the frame 9 and the rear side of collar member 6. Thus, mov'ement to the rear of tube I, and hence of the barrel B, is yieldingly resisted by the spring I4.

A hydraulic absorption apparatus I5 is also .provided This apparatus comprises a hollow cylindrical container .I6 which surrounds the rear portion of the tube I and extends about halfway within the spring I4. The cylinder I6 is supported by the interior cylindrical surface of frame member 9. Only a small portion I6`g of the cylinder surface within the frame member acts as a supporting surface, the remaining surface being of reduced diameter. Adjacent the end of cylinder surface I6g, there are provided unitarily formed lugs IBa, IBb, I6c, lGd. I6e, and I6! disposed around the periphery of cylinder I8. Longitudinal grooves 9a, 9b, 9c, 9d, 9e, and 9f are provided in the interior surface of frame member 9. These grooves permit passage of the lugs I6a, I6b, I6c, Id, ISe, and I6! when cylinder I 6 is inserted in frame member 9 from the front. A slight rotation of the cylinder I6 after insertion in frame member 9 thus makes the lugs Ilia, lsb, I6c, |601, ISe, and I6f abut against the end of the frame member 9 limiting frontal movement of the cylinder I6 with respect to the frame. Rearward movement of the cylinder I6 is prevented by a washer 26 which is inserted in a cylindrical recess Ia in the end of frame extension I Il. `In this position, the washer 26 engages the external shoulder I67 formed by the end of reduced diameter portion IBh provided on cylinder I6. Thus the cylinder I6 is secured to frame member 9 so far as relative longitudinal movement is concerned. The washer 26 may be made in two half pieces 26a and 26h (Fig. 6) for convenient assembly around cylinder I6.

At each end of the cylinder I6 a bearing I'I is inserted and suitably secured therein as by threads I'Ig. These bearings have relative small interior bearing surfaces I 1a engaging the tube I. The bearings I1 are each provided with a cylindrical extension I1b projecting within the container cylinder I6. The inner surfaces I'Ic of the extensions IIb are tapered, the diameter increasing toward the center of cylinder I6. The minimum diameter of this tapered portion is equal to the `minimum diameter of a piston I8 which is shaped like a collar and is detachably secured as by the threads IBd to the portion of the tube I intermediate the bearings. The transition surface between the end of taper I'Ic and bearing surface IIa provides a radial end wall ITd. The

v bearings I1.

position of the piston I8 on the tube I and the distance between the opposing end ywalls |1d of the tapered portions |1c are such that in the closed breech position of the barrel, a small clearance exists between one side of the piston member and the end I1d of the front bearing I1, while in the full recoil position of the barrel, a small clearance exists between the other side of the piston I8 and the end |`|d of therear bearing.4

The chamber defined by the bearing ends |1d,

A the exterior of tube I, and thev interior of container cylinder I8 is lled with a suitable hydraulic fluid. Leakage of the hydraulic iluid out through the bearing I1 is prevented by inserts e ofi suitable packing material. Ill-leid. in a recess I1e of the .bearings I1 by a hollow threaded bushing 2|) which cooperates with interior threads |1f provided in the extremities in the bearings |1.

The peripheral surface of the piston I8 is preferably provided with oppositely directed angular cuts I8a and |8b respectively parallel to the tapered surfaces I1c of the front and rear Very little resistance to the movement of the piston I8 will be encounteredl in the intermediate range of its movement due to the large clearance provided between the surfaces I 8a and I8b and the interior of cylinder I8. It will be apparent, however that as the tube I approaches either of its two extreme positions, a hydraulic force gradually increasing in magnitude will oppose such motion as the tapered lpiston member I8 is brought within the tapered walls I1c of the bearing I1.

Extending through the hollow interior of tube I, there is mounted the breech operating rod 2|. This rod is connected at its rear end to a member 22 constituting an extension of the breech mechanism (not shown). The rod 2| is supported at its rear end by an interior bearing surface provided in the hollow bushing 1. 0n the front end of rod 2|, a collar 23 is fastened and the exterior cylindrical surface of this collar 23 slidably engages the interior surface of the tube I. The movement to the front of the rod 2| is limited by the breech extension 22. The breech operating spring 24 ls inserted in the space defined between the interior surface of the tube I and the exterior surface of the rod 2|. The spring operates between the end of bushing I and the side of collar v28.

Any breech mechanism that will be forced to the rear by the recoil movement of the barrel may be utilized with the described recoil mechanism and accordingly no specific breech -mechanism is shown. The breech extension 22 is suitably secured to such breech mechanism.

A latch 30 (Figs. 7 and 8) is provided to coordinate the counter-recoil movement of the breech extension 22, and hence the breech mechanism with the counter-recoil movement of the barrel B. The latch 30 comprises a. bar pivoted at its center on a pin 3| transversely mounted in the frame 9 of the firearm between the barrel B and breech extension 22. A second transverse pin 32 acts as a stop to pivotal movement of the latch 30 and prevents the end of latch 30 from hitting the barrel B. 'A spring 33 exerts a force biasing the latch 30 against the stop 32. The top end of latch 38 is rounded and is depressed by a projection 34 on the barrel B when the barrel is in its firing position as shown in Fig. 7.

A collar 35 is provided on breech extension 22.

which engages the bottom end surface of latch 30 when the breech extension 22 is in its full recoil position (Fig. 8). The breech extension l22 and hence the breech is thereby latched in hollow tube I by the fitting 2 and bushing 1. The

movement of tube results in the compression of the recoil spring I4, through engagement of the head 5a of the bolt member 5 with the collar 8. Since the breech extension 22 moves with the barrel in its recoil, the breech operating rod 2| is also moved to the rear concurrently with the barrel. Thus the spring 24 is not substantially compressed. The piston I 8 is moved out of the front bearing I1 by movement of tube and apl proaches the rear bearing I1. Very little hy- This collar has an inclined surface 35a 7 draulic resistance to this movement is encountered until the piston enters the tapered portion |1c of the left hand bearing |1. Then the hydraulic resistance to further recoil movement is gradually increased, the rate of increase being dependent upon the slope of the surfaces I1c and |8b. The amount of energy hydraulically absorbed also depends on the slope of the taper. Just prior to the piston I8 reaching its extreme recoil position near the end |1d, the hydraulic resistance will be very great due to the small clearance provided for the escape of the hydraulic fluid between the piston surface I8b of the piston I8 and the surface I1c of the bearing I1. The energy thus absorbed by the spring |4 and the hydraulic mechanism I5 will reduce the recoil shock upon the stationary portion of the gun to a satisfactory magnitude.

Theinitial movement of the barrel removes extenson 34 from engagement with the top end of latch 30. permitting counterclockwise rotation of the latch by spring 33 until the stop 32 is engaged. In this position the latch 3|! engages the collar 35 on breech extension 22 when that member reaches its full recoil position, holding breech extension 22 in the full recoil position.

The barrel is now returned to firing position by means of the energy stored in the compressed spring I4. The hydraulic mechanism I5 operates on this counter-recoil movement to reduce the shock inherent at the end of this movement.

In this case, the piston I8 does not build up any hydraulic resistance to the movement to the front until it enters the tapered portion |1c of the front bearing A|1, then the hydraulic resistance is built up in the same manner as described for the recoil movement.

A very desirable feature of this construction lies in the fact that since the breech extension 22 is held latched by latch 38 in its full recoil fposition, thereby preventing the return of the breech rod 2| until the barrel has substantially completed its counter-recoil movement. the effect will be to compress the spring 24. This c^m pression has several desirable features in that it provides an additional energy absorption means for reducing the shock involved in the counterrecoil movement of the barrel, while at the same ordinary wrenches.

be made greater or less than the absorption during the recoil movement by inserting a bearing I1 in the front position having. a different slope of surface Ilc than the bearing in the rear position. Y

'I'he convenient method by which a recoil mechanism embodying the features of this invention may be disassembled from the barrel of the firearm has already been pointed out. Thus the barrel is made available for cleaning merely by backing oil the cylindrical nut Ic and pivoting the barrel clockwise to engage the tapered surfaces I2b and I21d of the opening I2. The breech end o f the lbarrel is thus raised above the breech mechanism (not shown) and the barrel may' slide to the rear out of engagement with the opening .I2 of the supporting member II.

The entire recon mechanism may be readilyy assembled or disassembled through the use of In the disassembly operation', the barrel B is disengaged from the other parts of the apparatus in the manner described.y The cylinder 8 is then unscrewed from the 'extension I0 of the frame member 9, and the cylinder 8, still screwed to the supporting member II, is disengaged from the apparatus. The bolt 5 is then unscrewed from the end of the tube I, permitting the collar 6 to be slipped oif the end of the tube, thus permitting the spring .I4 to be removed. 'Ihe cylinder I6 is then rotated slightly to bring the lugs Ilia, IGb, IIic, IBd, Ilie, and If into engagement with the longitudinal grooves 9a, 9b, 9c, 9d, 9e, and Bf. The cylinder I6 and its connected parts, namely, the |bearing I1 and the bushings 20, may then be pulled through the frame member 9, the bearing I'I and the bushings 2II sliding on the tube I. Having cleared vthe frame member 9, the parts of the hydraulic absorption mechanism may then be readily unscrewed and separated from the cylinder I6. This, of course, releases the hydraulic iiuid contained therein. If further disassembly is desired, the breech operating rod 2l may be unscrewed from its connection with the breech mechanism 22, and the rod 2| is thereby freed for withdrawal from the recoil tube I. The spring 24 may thereby be removed. The last disassembly operations may be the unscrewing of the bushing 1 from the'end of the tube I and the unscrewing of the cylinder 8, from the supporting member II.

Assembly of the apparatus is quickly accomplished, in general by reversing the assembly steps. One departure, however, should be mentioned, and thatris that the supporting member II?, should be screwed to the end of the cylinder 8, and then the collar 6 and the spring inserted within the cylinder. Then this assembly should Ibe installed by screwing the cylinder Il onto the extending member II) of the frame. By proceeding in this manner, the heavy spring I4 is very easily handled: and furthermore, the possibility of deforming it during the assembling operation is reduced. The bolt l should not be inserted in the end of the tube I until after the barrel has'been reassembled. Then tightening of the bolt 5 will have the effect of forcing the collar 8 back a slight distance on the tube I, sufficient to provide clearance between the collar and thel base IIb of the supporting member.

I claim:

1. In a recoil absorption mechanism for a firearm, a hydraulic energy absorption means comprising a recoiling member, a, stationary shell surrounding a portion of said recoiling member, bearing members mounted in each end of said shell Vand sealing the space between said shell and said recoiling member to define a fluid chamber, an annular piston mounted on said recoiling member intermediate said bearing members, said piston having two oppositely sloped annular surfaces, said slopes being unequal, and a parallel sloped interior surface on each 'bearing member closely surrounding the adjacent sloped piston surface when said recoiling member approaches either of its extreme positions of movement, whereby greater hydraulic energy absorption occurs for one direction of movement of the recoiling memberrrthan the other direction.

2.-In a ilrearm having a. recoiling barrel andY a breech mechanism movable therewith, a recoil mechanism comprising a tube connected to the recoiling barrel of the rearm, resilient means surrounding said tube and arranged to oppose the rearward movement of said tube, a rod mounted for movement within said tube and having one end connected to the breech mechanism, and a spring surrounding said rod and arranged to oppose yseparation of the barrel and breech mechanism.

3. In a firearm having a recoiling barrel and a breech mechanism movable therewith, a recoil mechanism comprising a tube connected to the recoiling barrel of the rearm, resilient means surrounding said tube and arranged to oppose rearward movement of said tube, stationary hydraulic means surrounding part of said tube and operating to resist movement of said tube, a rod mounted for movement within said tube and having one end connected to the breech mechanism, and a spring surrounding said rod and rranged to resist relative movement of said tube with respect to said rod and thereby oppose separation of the barrel and the breech mechanism. 4. In a firearm having a recoiling barrel and a breech mechanism movable therewith, a tube connected to said recoiling barrel, a iirst resilient means surrounding said tube and opposing the rearward movement of said tube, a, rod connected to said breech mechanism and mounted for movement within said tube, a second resilient means opposing frontal movement of said tube relative to said rod; and means latching the breech mechanism in opened position until the barrel completes its counter-recoil movement whereby the second resilient means is compressed to provide a breech closing force.

5. In a i'lrearm having a recoiling barrel and I ya breech mechanism movable therewith, a tube i connected to said recoiling barrel, a first cylinoppose frontal movement of said tube relative to said rod, and means latching the breech mech anism in opened position until the barrel cornpletes its counter-recoil movement whereby the second cylindrical spring is compressed to provide a breech closing force.

6. In a firearm having a recoiling barrel and a breech mechanism movable therewith, a tube connected to said recoiling barrel, a rst resilient means surrounding said tube and opposing the rearward movement of said tube, a stationary hydraulic cylinder surrounding said tube, an annular piston mounted on said tube cooperating with the hydraulic cylinder surrounding the tube to hydraulically oppose movement of the tube in either direction of movement, a rod connected to said breech mechanism and mounted for movenient within said tube, a second resilient means Opposing rfrontal movement of said tube relative to said rod; and means latching the breech mechanism in opened position until the barrel completes its counter-recoil movement whereby the second resilient means is compressed to provide a breech closing force.

7. In a firearm having a recoiling barrel and a breech mechanism movable therewith, a tube connected to said recoiling barrel, a first cylindrical spring surrounding said tube and connected between said tube and a stationary part of the rearm to oppose the rearward movement of said tube, a stationary hydraulic cylinder surrounding said tbe, an annular piston mounted on said tube cooperating with the hydraulic cyl inder surrounding the tube to hydraulically oppose movement of the tube in either direction of movement, a rod mounted for movement within said tube and having one extending end connected to said breech mechanism, a second cylindrical spring mounted around said rod and arranged to oppose frontal movement of said tube relative to said rod, and means latching the breech mechanism in opened position until the barrel completes its counter-recoil movement whereby the second cylindrical spring is compressed to provide a breech closing force.

8. In a rearm, having a recoiling barrel and a stationary recoil absorption mechanism, bifurcated means detachably securing one end of the recoil mechanism in spaced relationship to the barrel, and barrel supporting means at the other end of the recoil mechanism comprising a bracket having a portion arranged to receive said recoil absorption mechanism and another transversely extending portion comprising a collar, said collar having interior bearing surfaces arranged to engage the barrel in its recoil movements and inciined surfaces arranged to permit pivotal movement of the barrel within the collar and withdrawal of the barrel through the collar.

CLARENCE E. SIMPSON. 

